The aim of the experiment is to determine the crystal structures of BphD and biphenyl dioxygenase with primary phase detennination. The upstream pathway for the aerobic biodegradation of aromatic compounds typically involves four initial steps: (1) dihydroxylation of a ring by a dioxygenase to form a cis-dihydrodiol product; (2) dehydrogenation to form a dihydroxy aromatic product; (3) ring cleavage by a dioxygenase; (4) hydrolysis of the ring-fission product by a serine hydrolase. We are studying the structure and function of the enzymes that catalyze these steps in the biodegradation of PCBs (polychlorinated biphenyls) with the goal of understanding the biochemistry and developing bacterial strains that are enhanced in their ability to degrade the full range of PCBs. This science is applicable to a relatively large number of homologous pathways for the degradation of another xenobiotic aromatic compounds of health, environmental, or industrial significance. Use of BioCARS Station 14-BM-D using MAD technique.